Lennox CBK45UHVT Series Unit Information

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Service Literature

WARNING

Improper installation, adjustment, alteration, service

or maintenance can cause property damage, personal

injury or loss of life. Installation and service must be

performed by a licensed professional HVAC installer or

equivalent, service agency, or the gas supplier.

IMPORTANT

The Clean Air Act of 1990 bans the intentional venting of

refrigerant (CFCs, HCFCs and HFCs) as of July 1, 1992.

Approved methods of recovery, recycling or reclaiming

must be followed. Fines and/or incarceration may be

levied for noncompliance.

NOTICE

A thermostat is not included and must be ordered

separately.

• A Lennox communicating thermostat must be used in

communicating applications.

• In non-communicating applications, the Lennox

ComfortSense® thermostat may be used, as well as

other non-communicating thermostats.

In all cases, setup is critical to ensure proper system

operation.

Field wiring for both communicating and non-

communicating applications is illustrated in diagrams,

which begin on page 29.

CAUTION

As with any mechanical equipment, contact with sharp

sheet metal edges can result in personal injury. Take

care while handling this equipment and wear gloves and

protective clothing.

UNIT INFORMATION

May 20, 2025

CBK45UHVT (R454B) SERIES UNITS

Page 1

100111

Table of Contents

Unit Dimensions – Upflow ............................................6

Specifications and Electrical Data ..................................7

Model Number Identification ...........................................8

Adjusting the BDC3 Blower Control ...............................8

Adjusting the Blower Speed ..........................................8

BLOWER DATA ............................................................10

Application ....................................................................18

Unit Components ..........................................................18

ECB45 Electric Heat ....................................................20

Heat Section Installation ...............................................25

Configuration Modification ...........................................27

Sensor / Bracket Installation .........................................31

Brazing Connections ...................................................32

Leak Testing, Evacuating and Charging .......................33

Installing the Condensate Drain ..................................37

Electrical Connections .................................................39

Inspecting and Replacing Filters .................................40

Wiring Diagrams ...........................................................41

Professional Maintenance ...........................................43

Sensor Maintenance ....................................................43

Check-out Procedures .................................................43

Sequence of Operation ................................................44

Modes of Operation ......................................................44

Start Up Test Procedure ...............................................46

Decommissioning ........................................................47

General Information

This indoor unit with all-aluminum coil is designed for

installation with optional field-installed electric heat and

a matched outdoor unit that is charged with R454B re-

frigerant. These units, designed for indoor installation in

multiple positions, are completely assembled for upflow

and horizontal right-hand discharge before being shipped

from the factory.

All CBK45UHVT air handlers are equipped with a facto-

ry-installed, internally mounted check / expansion valve,

which is suitable for use in R454B applications.

This air handler is compatible with the ComfortSense®

non-communicating thermostat and non-communicating

outdoor units. In addition, this unit has the enhanced ca-

pability of communicating with communicating thermo-

stats and communicating outdoor units using the Lennox

RSBus protocols.

NOTE - For downflow or horizontal left-hand air discharge,

certain field modifications are required.

IMPORTANT: Special procedures are required for clean-

ing the all-aluminum coil in this unit. See page 43 in this

instruction for information.

CBK45UHVT

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Summary of Contents for Lennox CBK45UHVT Series

Page 1 R454B re- • A Lennox communicating thermostat must be used in frigerant. These units, designed for indoor installation in communicating applications. multiple positions, are completely assembled for upflow •...
Page 2 WARNING CAUTION • Do not use means to accelerate the defrosting pro- Under no circumstances shall potential sources of cess or to clean, other than those recommended by ignition be used in the searching for or detection of the manufacturer. refrigerant leaks.
Page 3 IMPORTANT IMPORTANT When breaking into the refrigerant circuit to make When removing refrigerant from a system, either for repairs – or for any other purpose – conventional servicing or decommissioning, it is recommended good procedures shall be used. However, for flammable practice that all refrigerants are removed safely.
Page 4 IMPORTANT IMPORTANT Prior to beginning work on systems containing Where electrical components are being changed, they FLAMMABLE REFRIGERANTS, safety checks are shall be fit for the purpose and to the correct specification. necessary to ensure that the risk of ignition is minimized. At all times the manufacturer’s maintenance and service guidelines shall be followed.
Page 5 WARNING CAUTION For duct connected appliances, false ceilings or Any service personnel installing, decommissioning, or drop ceilings may be used as a return air plenum if a performing maintenance on the unit must be properly REFRIGERANT DETECTION SYSTEM is provided in trained with A2L refrigerants the appliance and any external connections are also provided with a sensor immediately below the return air...
Page 6 Unit Dimensions – Upflow 1 (25) DETAIL OF PIPING PLATE 4-3/4 3/4 (19) (121) SUCTION LINE SUPPLY AIR LIQUID OPENING CONDENSATE LINE 14-1/2 DRAINS (2) (368) 2-3/8 (Horizontal) (60) 1 (25) 1 (25) CONDENSATE DRAINS (2) 4-3/8 (Upflow and (111) 2-3/4 Downflow) LOW VOLTAGE...
Page 7 Specifications and Electrical Data Size Nominal Tonnage Refrigerant Type R-454B R-454B R-454B R-454B Factory Installed Expansion Valve (TXV) 26Z70 26Z70 26Z70 26Z70 Connections Liquid line (OD) sweat - in. Suction line (OD) sweat - in. Condensate drain (FPT) - in. (2) 3/4 (2) 3/4 (2) 3/4...
Page 8 Model Number Identification CB K 45 UH V T - 036 - 230 - 71 Unit Type Revision Level CB = Air Handler 71 = R-454B TXV installed Voltage 230 = 208/230V-1 phase-60hz Refrigerant Type K = R-454B Nominal Cooling Capacity 018 = 1.5 tons 024 = 2 tons Series...
Page 9 COOL COOL HEAT HEAT CBK45UHVT-042 PIN #3 PIN #3 PIN #3 PIN #3 Applications with the Lennox ComfortSense® 7500 ther- mostat, but no demand for de-humidification will operate COOL COOL HEAT HEAT CBK45UHVT-048 PIN #3 PIN #3 PIN #3...
Page 10 1050 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 250 cfm. ® CBK45UHVT-018 BLOWER MOTOR WATTS AT “+”...
Page 11 1050 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 250 cfm. ® CBK45UHVT-024 BLOWER MOTOR WATTS AT “+”...
Page 12 1100 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 250 cfm. ® CBK45UHVT-030 BLOWER MOTOR WATTS AT “+”...
Page 13 1330 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 250 cfm. ® CBK45UHVT-036 BLOWER MOTOR WATTS AT “+”...
Page 14 1490 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 450 cfm. ® CBK45UHVT-042 BLOWER MOTOR WATTS AT “+”...
Page 15 1885 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 450 cfm. ® CBK45UHVT-048 BLOWER MOTOR WATTS AT “+”...
Page 16 1890 NOTES - First stage cooling air volume is 70% of COOL speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox LZSV Variable Zoning System applications - minimum blower speed is 450 cfm. ® CBK45UHVT-060 BLOWER MOTOR WATTS AT “+”...
Page 17 TABLE 2. CBK45UHVT Thermostat and Single-Stage Outdoor Unit Operating Sequence Operating Sequence System Demand System Response Thermostat Demand Relative Humidity Handler System Step Comments Condition pressor Status (COOL) NO CALL FOR DEHUMIDIFICATION Normal Operation Acceptable 24 VAC High 100% low thermostat demand BASIC MODE (only active on a Y1 thermostat demand) Normal Acceptable...
Page 18 C- Motor runs at 100% until demand is satisfied. TRANSFORMER D- Once demand is met, motor ramps down to stop. All CBK45UHVT series units use a single line voltage to 24VAC transformer mounted in the control box. The transformer supplies power to the control circuits in the indoor and outdoor unit.
Page 19 BLOWER ASSEMBLY PRIMARY SECONDARY ORANGE BLUE 240 VOLTS 208 VOLTS BLACK YELLOW FIGURE 3. 208 / 240 Volt Transformer BLOWER RELAY All CBK45UHVT units use a double-pole single-throw (DPST) switch relay to energize the blower motor. The FIGURE 4. Blower Assembly relay coil is energized by blower demand from indoor COIL thermostat.
Page 20 ECB45 Electric Heat EL ECTR I C HEAT DATA C B K4 5U H V T- 01 8 | S I N G L E PH A SE Blower Minimum Maximum Input Electric Heat Motor Circuit Overcurrent Model Number Full Load Ampacity Protection Volt...
Page 21 EL ECT RI C HEAT DATA CBK45UHVT- 030 | S ING LE P HASE Minimum Maximum Single Point Input Circuit Overcurrent Blower Power Source Ampacity Protection Electric Heat Motor Full Load Model Number Minimum Maximum Amps Volt Btuh Ckt 1 Ckt 2 Ckt 1 Ckt 2...
Page 22 EL ECT RI C HEAT DATA CBK45UHVT- 036 | S ING LE P HASE Minimum Maximum Single Point Input Circuit Overcurrent Blower Power Source Ampacity Protection Electric Heat Motor Full Load Model Number Minimum Maximum Amps Volt Btuh Ckt 1 Ckt 2 Ckt 1 Ckt 2...
Page 23 EL ECT RI C HEAT DATA CBK45UHVT- 042 | S ING LE P HASE Minimum Maximum Single Point Input Circuit Overcurrent Blower Power Source Ampacity Protection Electric Heat Motor Model Number Full Load Minimum Maximum Amps Volt Btuh Ckt 1 Ckt 2 Ckt 1 Ckt 2...
Page 24 EL ECTR IC HEAT D ATA C B K4 5 U H V T- 0 4 8 | C B K 4 5 U H V T- 0 6 0 | S I N GL E P H A S E Minimum Maximum Single Point...
Page 25 6 - Secure the electric heater assembly into place Heat Section Installation with the screws that were removed from the heat element panel. Install two field-provided #8 SDST WARNING screws in the front of the electric heater assembly (see figure 6). Before installing or servicing unit, be sure ALL power to the unit is OFF.
Page 26 IMPORTANT NOTE - There may be only one clip securing each circuit breaker. USE COPPER CONDUCTORS ONLY BREAKER(S) MOUNTING CIRCUIT BRACKET BREAKER NOTE – Refer to the nameplate on the air handler unit for minimum circuit ampacity and maximum overcurrent protection size.
Page 27 Configuration Modification CIRCUIT BREAKER COVER (BACKSIDE) UPFLOW APPLICATION 1 - The air handler must be supported on the bottom only and set on solid floor or field-supplied support frame. Securely attach the air handler to the floor or support frame. 2 - If installing a unit in an upflow application, remove the horizontal drain pan.
Page 28 NOTE – When the unit is installed in horizontal applica- TOP CAP ROTATED TO tions, a secondary drain pan is recommended. Refer to CORRECT POSITION local codes. TOP CAP SCREWS CABINET SUPPORT NOTE – This unit may be installed in left- or right-hand air discharge horizontal applications.
Page 29 NOTE – For horizontal applications in high humidity ar- IMPORTANT eas, remove the downflow rail closest to the drain pan. To remove rail, remove screw from rail at back of unit and at If electric heat section with circuit breakers (ECB45) is cabinet support rail.
Page 30 1 5/8 (41) TOP VIEW 11 3/8 (289) 1 5/8 (41) 23-1/4 (591) 20 (508) 1 5/8 (41) SUPPLY AIR OPENING 22 5/8 (575) -018/024 INCHES (MM) 24 5/8 (625) -030, 036 26 5/8 (676) -042, 048, 060 13 1/2 (343) 5/8 (16) OPENING 3 (76)
Page 31 Sensor / Bracket Installation Vertical Configuration Leak detection sensor and bracket are factory-installed for vertical installation. No sensor relocation is required if in- stalling in vertical configuration. NOTE – The leak detection sensor needs to be relocated for horizontal right, horizontal left, and downflow configu- rations.
Page 32 4 - Loop any excess wire through the plastic “M” wire clip located on the inside of the center support bracket. Downflow Configuration 1 - Remove sensor bracket assembly from vertical position. Do not remove sensor from bracket, and do not disconnect or reroute sensor wire from the control panel area.
Page 33 NOTE - When installing refrigerant lines longer than 50 feet, see the Lennox Refrigerant Piping Design and Fab- • All field joints shall be accessible for inspection prior to rication Guidelines, CORP. 9351-L9, or contact Lennox being covered or enclosed Technical Support Product Applications for assistance.
Page 34 1. The actual refrigerant charge is in accordance with the tion equipment shall be calibrated in a refrigerant-free room size within which the refrigerant containing parts area.) Ensure that the detector is not a potential source are installed. of ignition and is suitable for the refrigerant used. Leak detection equipment shall be set at a percentage of the 2.
Page 35 IMPORTANT In addition to conventional charging procedures, the following requirements shall be followed. • Ensure that contamination of different refrigerants does not occur when using charging equipment. Hoses or lines shall be as short as possible to minimize the amount of refrigerant contained in them. •...
Page 36 PLEASE READ IMPORTANT ISSUES CONCERNING BRAZING OPERATIONS ON PREVIOUS PAGES BEFORE PROCEEDING. NOTE - REFER TO OUTDOOR UNIT INSTALLATION INSTRUCTIONS FOR REFRIGERANT PIPING SIZE REQUIREMENTS. NOTE - Use silver alloy brazing rods with five or six percent minimum silver alloy for copper-to-copper brazing, 45 percent alloy for copper-to-brass and copper-to-steel brazing.
Page 37 METERS) LENNOX P-TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J-TRAP 91P90. PIPE NIPPLE PROVIDED IN BAG ASSEMBLY - SCH 80, 3/4” I. D. X 5” - 34K7401 (1): CUT THE PIPE IN HALF AND USE IT TO ROUTE THE MAIN DRAIN.
Page 38 1 - Remove the appropriate drain knockouts. If 3 - Correct any leaks found. necessary, remove the indoor coil assembly from BEST PRACTICES the cabinet. The following best practices are recommended for the 2 - Connect primary drain line connection to the primary condensate removal process: drain pan connection.
Page 39 If installed in an unconditioned space, sealant should be IMPORTANT applied around the electrical wires, refrigerant tubing, and condensate lines where they enter the cabinet. Refrigerant lines must be clean, dehydrated, refrigerant- grade copper lines. Air handler coils should be installed WARNING only with specified line sizes for approved system combinations.
Page 40 • This air handler is factory-configured for 240 volt, single 208 / 240 VOLT TRANSFORMER phase, 60 cycles. For 208-volt applications, see “208 Volt Conversion” later in this section. PRIMARY SECONDARY • For optional field-installed electric heat applications, re- fer to the instructions provided with the accessory for proper installation.
Page 41 Wiring Diagrams SYSTEM FIELD JUMPERS WARNING SINGLE STAGE AIR CONDITIONER NEED ALL TWO-STAGE AIR CONDITIONER REMOVE Y1 TO Y2 SINGLE STAGE HEAT PUMP REMOVE R TO O USE COPPER CONDUCTORS REMOVE Y1 TO Y2 AND R TWO-STAGE HEAT PUMP TO O ONLY TWO-STAGE ELECTRIC HEAT REMOVE W1 TO W2...
Page 42 WARNING USE COPPER CONDUCTORS ONLY FIGURE 34. Low Voltage Connections (Variable-Speed Motor) Page 42...
Page 43 (less than 50psi). If the refrigerant gas. Heat from the tubing may melt the wiring coil cannot be cleaned using water alone, Lennox insulation, causing a short circuit. recommends use of a coil cleaner with a pH in the range of 5 to 9.
Page 44 Use of Air Handler During Construction If the room temperature should continue to fall, the cir- Lennox does not recommend the use of its air handler unit cuit between R and W1 is completed by the second-stage during any phase of construction. Very low return air tem- heat room thermostat.
Page 45 3 - After the RDS Non-Communicating Blower Control TABLE 7. Red LED Diagnostic Codes Board determines the refrigerant levels are below the Applies to Issue Action safety threshold, the blower will continue to function for Flash Individual an additional seven (7) minutes. Sensor(s) Check for 24VAC power 4 - After the blower sequence is complete, the HVAC sys-...
Page 46 After the purge sequence is complete, the zone system Thermostat Compatibility will resume normal operation. Thermostats that preserve memory settings are compat- External Alarm ible with the RDS Non-Communicating Blower Control (For applications with external alarms wired directly to the Board.
Page 47 Diagnostic Codes and Troubleshooting TABLE 10. LED Diagnostic Codes State LED Diagnostic Code Action Required Initializing Flashing green None Solid green. Monitoring If a prior mitigation occurred, a blue flash None interrupts the solid green LED. Mitigating Check coil tubes for leak. Repair the issue and restart the equip- Flashing blue (Leak Detected) ment.
Page 48 Installing Contractor’s Name_______________________ Installing Date_______________________________ Installing Contractor’s Phone_______________________ Air Handler Model #___________________________ Job Address____________________________________ Thermostat Line Voltage SUPPLY Disconnect Switch Temperature Integrated Control Duct Blower Motor Amps System Electric Heat Amps Duct Static RETURN Filter Drain Line DUCT SYSTEM TOTAL EXTERNAL STATIC (dry coil) dry coil wet coil SUPPLY AIR DUCT...
Page 49 Installing Contractor’s Name_______________________ Installing Date_______________________________ Installing Contractor’s Phone_______________________ Air Handler Model #___________________________ Job Address____________________________________ Line Voltage Disconnect Switch Thermostat Integrated Control Duct System Duct System Filter RETURN SUPPLY Electric Heat Amps Blower motor Amps Drain Line Duct Static Temperature DUCT SYSTEM TOTAL EXTERNAL STATIC (dry coil) dry coil wet coil...

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